Reference Manual

setm - set the MTU for a specified inteface.

setm ifn [mtu]

When invoked with only the ifn argument, setm prints the current NAT32 Maximum Transfer Unit (in decimal) for the specified interface. Argument ifn can also be the value p to denote the Primary Interface.

Argument mtu can specify a non-standard MTU for the specified interface. For some implementations of the PPPoE protocol, an MTU of 1412 should be specified.

The altered settings are not recorded in any netcfg file or in the Windows Registry. To make the settings permanent, the command should be placed in file startup.

The MTU adjusment has the effect that maximum length (1500 byte) packets arriving from a private machine will be discarded and an ICMP packet indicating the MTU will be sent back to the original source of the packet. Windows will then ensure that all future packets do not exceed the new MTU, thus making it unnecessary to change the MTU on the private machines.

mtu netcfg pppoe setp